1. Field of the Invention
The present invention relates generally to obstetrical instruments and more particularly to a device for simultaneously cutting and clamping an umbilical cord and to clips for use in combination with the device.
2. Brief Description of Prior Art
Surqical instruments for simultaneously severing and clamping the umbilical cord of a newborn infant are known. For example, U.S. Pat. Nos. 640,517, 2,052,870, 2,060,724, 3,166,071, and 4,428,374 each disclose clamping devices for simultaneously cutting the umbilical cord and clamping both the maternal and the fetal ends of the severed cord. The devices generally employ a pair of clamps which are detachable or removable from the clamping device after the cord has been severed and clamped. These devices generally have a simple scissors-like configuration, the force manually exerted by an operator on the handle of the clamping device being transmitted through a single pivot or fulcrum to the clamping and severing means.
U.S. Pat. No. 3,631,858 discloses a device or a device for simultaneously clamping and severing the umbilical cord in a single operation requiring only one hand, no detachable clamps being employed.
U.S. Pat. No. 4,648,401 discloses a scissors-like surgical instrument for severing an umbilical cord employing a single umbilical cord clamp and a single-use, disposable blade assembly to sever the cord. The instrument permits the release of the clamp or hemostat on the maternal end of the umbilical cord immediately after the cord is cut for collection of a blood specimen for a fetal Rh factor screen test to avoid discomforting the infant by obtaining the specimen directly from the infant.
In general it is desirable in obstetrical practice to sever and securely clamp both ends of the severed umbilical cord as quickly as possible. This is especially so when complications arise during the delivery such as when the umbilical cord is wrapped around the infant's neck. The fetal end of the severed cord must be securely clamped so that during the drying and consequent shrinkage of the cord which occurs after delivery further bleeding, infection, or umbilical hernia do not occur.
The prior art devices generally share a common disadvantage in that they are adapted for use in severing and clamping umbilical cords having a relatively small diameter. However, in obstetrical practice the range in diameter of the umbilical cords encountered is substantial (e.g., about 1-2.5 cm), and the prior art devices are generally not suitable for severing and clamping cords having relatively large diameters. As umbilical cords include tough, gelatinous, fibrous tissue (Wharton's jelly), as well as two arteries and a vein, scissors-like devices may not provide sufficient force to cleanly sever them. Further, the scissors-like prior art severing and clamping devices apply severing and clamping forces to the cord which vary inversely with the distance from the fulcrum or pivot point. This manner of applying forces to the cord can cause substantial problems, especially when large diameter cords are to be cut and clamped. For example, the force applied to clamp the cord proximate the fulcrum of the device can exceed the force required to tear or cut the cord, thereby permitting hemorrhaging of the cord adjacent to the clamp end. Similarly, the force applied to clamp the portion of cord furthest removed from the fulcrum of a scissors-like device may be insufficient to securely clamp the cord, thereby providing the same undesired result.
Thus, there is a need for a surgical instrument for severing and clamping the umbilical cord of substantially varying diameter while simultaneously avoiding the application of excessive force which would otherwise damage the clamped cord resulting in undesired bleeding and/or which tends to clamp a portion of the cord with insufficient force thereby permitting bleeding through the insufficiently clamped severed cord end.
Further, there is a need for a surgical instrument which can minimize the time which an obstetrician must expend in cutting and securely clamping the ends of the umbilical cord during delivery.